drm/fb_helper: Disable all crtc's when initial setup fails.

commit 52dd06506e9bbc2a37b352df7dfc5468f8da21fd upstream.

Some drivers like i915 start with crtc's enabled, but with deferred
fbcon setup they were no longer disabled as part of fbdev setup.
Headless units could no longer enter pc3 state because the crtc was
still enabled.

Fix this by calling restore_fbdev_mode when we would have called
it otherwise once during initial fbdev setup.

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Fixes: ca91a2758fce ("drm/fb-helper: Support deferred setup")
Reported-by: Thomas Voegtle <tv@lio96.de>
Tested-by: Thomas Voegtle <tv@lio96.de>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20171128111603.62757-1-maarten.lankhorst@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
index 1b8f013ffa6503ec960cee3bdb9cb7c3fa78d2bc..5e93589c335cb69f3c703e592627e48e23cab295 100644 (file)
--- a/drivers/gpu/drm/drm_fb_helper.c
+++ b/drivers/gpu/drm/drm_fb_helper.c
@@ -1809,6 +1809,10 @@ static int drm_fb_helper_single_fb_probe(struct drm_fb_helper *fb_helper,
 
        if (crtc_count == 0 || sizes.fb_width == -1 || sizes.fb_height == -1) {
                DRM_INFO("Cannot find any crtc or sizes\n");
+
+               /* First time: disable all crtc's.. */
+               if (!fb_helper->deferred_setup && !READ_ONCE(fb_helper->dev->master))
+                       restore_fbdev_mode(fb_helper);
                return -EAGAIN;
        }